The modulation of opioid peptide-containing proteins (OPCPs) in the human pituitary proteome will be characterized by comparing data from controls and tumors, OPCPs will be detected with a new analytical method, and those OPCPs will be characterized with a rapid, objective, and panoramic analytical method. Controls and tumors (secreting tumors, non-secreting tumors) will be studied because it is hypothesized that the proteome will differ in these two different types of tissue. This hypothesis is based on preliminary data that demonstrate a difference in the proenkephalin A and proopiomelanocortin (POMC) systems in several different human pituitary tumors. Two dimensional gel electrophoresis (2D GE) separation of proteins will be coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF- MS) analysis of all OPCPs. Also, all proteins that demonstrate a significant difference (absent vs. present; increased vs. decreased amount) between controls and tumor pituitaries will be studied. Post- source (PSD) analysis of tryptic peptides will provide the amino acid sequence data. Specific Aim 1: 2D GE of the proteome of the human pituitary (controls and tumors) will be performed. MALDI MS will characterize each OPCP, and any other protein that is significantly different in these two electrophoretic patterns. Specific Aim 2: In-gel trypsinolysis will be performed on, first of all, each protein that is significantly different between control versus tumor pituitary All OPCPs will be detected with a specific set of "marker peptides" following trypsinolysis. Specific Aim 3: For each OPCP, or for each protein that is significantly different between the two different types of pituitary electrophoretic patterns, MALDI-TOF will be used to characterize the protein. First, the molecular weight of the protein will be determined. Second, tryptic maps will be used to characterize the particular protein. That information will be combined with the sequence information that is available in databases to characterize the protein. This study is part of a larger program that will monitor tachykinin, orphanin, and other selected (GSH, prolactin, FSH, TSH) neuropeptidergic systems.